Pump



June 4, 1963 w. G. WUNDER 3,092,030

PUMP

Filed July 10, 1961 INVEN 0R.

75750177 6' 2; er az/fzfl AT RNEY United States Patent 3,092,030 PUMPFiled July 10, 1961, Ser. No. 122,720 1 Claim. (Cl. 103-103) Thisinvention relates to a pump for lifting and conveymg molten metal andmore particularly to a pump adapted for immersion in a corrosive moltenmetal such as aluminum.

Modern light metal foundry operations require that molten metal such asaluminum or magnesium be conveyed in relatively small quantities atfrequently recurring intervals from a holding furnace or the like wherethe metal is stored in a molten condition to molds or the like, as forexample, the shot sleeve of a cold chamber die casting machine. Manyattempts have been made in the past to develop satisfactory ways ofpumping molten metal in this manner. The great difficulty has been toprovide a pump in which the parts exposed to contact with the moltenmetal will resist the deleterious attack thereof and which is ofsufiiciently simple construction to permit its fabrication of suitablecorrosion-resistant materials. In the case of-pumping molten aluminum,metal pump parts are unsatisfactory since high melting point metals,such as iron, are dissolved when in contact with molten aluminum inspite of the fact that the temperature of the molten aluminum may beapproximately one half the melting temperature of the iron. The life ofpump parts which operate immersed in molten aluminum is as a consequencerelatively short, in the neighborhood of a few days or less when usedcontinuously. Moreover, the iron which is thusly introduced into themolten aluminum in substantial quantities constitutes an undesirableimpurity which may adversely affect the quality of the castings. Othermolten metals attack and adversely affect other higher meltingtemperature metals in a similar manner.

It is a basic object of this invention to provide a pump for pumpingmolten metals such as aluminum which is efiicient in its operation andwhich may be readily and economically formed of materials capable ofresisting deleterious attack by the molten metal.

These and other objects are accomplished by a novel pump structureconsisting essentially of a housing containing a vertically disposedcylindrical passage therein including an inlet and an outlet androtatably mounted therein a rotor consisting of a circular body definedby a circular periphery and top and bottom oppositely disposed faces orsurfaces. The top of the rotor body is attached to a vertically mountedpump shaft. The base of the rotor is provided with an opening extendingupwardly therein. A series of open-ended passages extend from thisopening radially outwardly and upwardly to an offset or reduced diameterportion extending downwardly from the top of the rotor. In operation,when the rotor is immersed in molten metal and caused to spin, themolten metal is drawn into the opening within the rotor and thenceimpelled radially outwardly to the reduced diameter portion thereof. Avertically disposed vane projecting into the pump passage translates therotational movement of the molten metal to upward and substantiallylineal motion.

Other objects and advantages of the invention will become apparent fromthe following detailed description of the invention, reference being hadto the accompanying drawings, in which:

FIGURE 1 is an elevation view in partial cross section of a pumpembodying the present invention;

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FIGURE 2 is an end view taken along line 2-2 of FIGURE 1; and

FIGURE 3 is an exploded view showing various components of the pump ofFIGURE 1 in perspective.

Referring to the drawings, FIGURE 1 illustrates one embodiment of thepump made in accordance with the present invention which is particularlydesigned for pumping molten metal from a retaining crucible or furnaceinto the trough of a cold chamber-type die casting machine. In general,the pump is of a centrifugal type, including a housing 10 having acylindrical passage 11 therein which forms an inlet opening 12 at thebase thereof. An outlet opening 14 is provided near the top of thehousing. Operating Within the housing 10 is an impeller or rotor 16mounted on a shaft 18. The top 15 of the housing is closed except forthe provision of an opening 21 through which the rotor shaft passes.

As may be seen most clearly in relation to FIGURE 3, the impeller 16consists of an annular block having a top side 17 and a bottom side 19and having a reduced diameter portion 20 extending downwardly from thetop side 17. Centrally of the impeller at the base thereof there isprovided an annular intake chamber 22. A plurality of diagonal passages24 extend from the intake chamber 22 to the reduced diameter portion 20.

The impeller 16 is threadably attached to a shaft 18 preferablyconsisting of a steel core 28 and an outer body portion 30. The steelcore 28 permits the body portion 30 to be made of a relatively weak orbrittle refractory material which is capable of resist-ing the erosionof the molten aluminum. Conveniently the impeller may be formed to havea passage entirely through the center thereof, the base 32 of the shaftserving as a closure or top of the intake chamber 22 of the impeller.

The passage 11 in the housing portion 10 of the pump includes an annularportion 34 at the base thereof adapted to receive the impeller 16 so asto provide a small clearance 36 therebel-ow so that when the base of thepump is immersed in molten aluminum the impeller is not apt to engage arigid surf-ace even if the pump is placed on the base of a crucible. Thepassage 11 includes a longitudinal vane 38 interiorly thereof extend-ingfrom a position just above the impeller 16 to a point in close proximityto the pump outlet 14.

The pumping action of the pump may be readily understood in relation toFIGURE 3. To pump the molten aluminum the unit is inserted in the moltenmetal to a sufficient extent to cause the intake chamber 22 of theimpeller 16 to be immersed in the molten aluminum and filled therewith.Normal hydrostatic pressure will, of course, cause the molten aluminumto flow into the intake chamber 12 of the impeller. When the impeller iscaused to spin, the aluminum is thrown to the periphery of the chamber22 and onward through the diagonal openings 24 to the annular space 23formed between reduced portion 20 of the impeller and passage 11. Thelongitudinal vane 3-8 within the chamber 11 causes the whirling motionof the molten aluminum to be translated into linear motionlongitudinally of the pump housing passage 11 and onto the outlet 14thereof.

As previously indicated, the pump of this invention is particularlydesigned to be formed of relatively brittle refractory materials. Theimpeller may be formed of a refractory material such as carbon. Aspreviously indicated, the impeller structure preferably involves the useof a steel core 28 as shown in FIGURE 3 which is wrapped with asbestosstrip or covered with outher suitable ceramic material. The steel core28 is cemented to the covering material 30 and takes the torque indriving the impeller.

In some instances, the pump components may be made of a heat-resistantalloy such as the well known ironnickel-chromium types to which is fuseda ceramic coating to prevent molten metal such as aluminum fromattacking these pump parts when subjected to direct and prolongedcontact with such a molten metal. A suit able protective ceramic coatingmay be applied by first spraying a composition which has a high contentof ironnickel-chromium and manganese oxides and a low content ofaluminum, then spraying several additional coatings, each having aprogressively greater aluminum oxide content so that the final spraycoat has a very high aluminum oxide content and then fusing and bondingthese coatings to the base metal. The simple structure of the pumpcomponents simplifies the application of this type of coating.

While the embodiment of the present invention as disclosed hereinconstitutes a preferred form, it is to be understood that other formsmay be adopted without departing from the spirit of the invention.

I claim:

Apparatus for pumping molten metal from one level to a higher leveladapted to be formed of relatively britt le non-metallic refractorymaterials comprising a longi tud-inal housing having a cylindricalpassage therethrough, a rotor mounted on a shaft positioned within saidcylindrical passage near the open-ended base of said housing, an outletconduit communicating with said passage above said rotor, said rotorcomprising a generally circular body defined by a circular periphery andupper and low er opposite faces, an opening in said lower face andextending into said body, said shaft extending into said body at theupper face and being fixed to said body, said shaft being formed of anonmetallic refractory and having a metal core, said circular bodyhaving a reduced diameter portion at the upper end thereof, said reduceddiameter portion and said passage forming an annular recess, andopen-ended passages extending radially through said body from saidopening to a plurality of locations around the periphery of said reduceddiameter portion of said body, whereby when said rotor assembly isrotating in a molten metal bath the molten metal is drawn upwardly intosaid opening and thence; impelled radiallyoutwardly to saidrecess, and alongitudinal vane formed integrally with said housing extending from, apoint above said rotor to a point near to said outlet, said vane beingoperative to translate rotational to longitudinal movement within saidhousing.

References Cited in the file ofsthis, patent UNITED STATES PATENTS849,030 Valliquette Apr, 2, 1907 1,832,890 Antisell ,Nov. 2.4, 19312,493,467 Sunnen Jan. 3, 1950 2,528,210 Stewart Oct. 31, 1950 2,658,454Greene NOV. 10, 1953 2,905,093 Raut et al. Sept. 22, 1959 2,948,524Sweeney et a1 Aug. 9, 1960 3,048,384 Sweeney et a1. Aug. 7, 1962

